* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body{
    height: 100vh;
    display: flex;
}
.tab{
    margin: auto;
    width: 500px;
    --height:50px;
    height: var(--height);
    display: flex;
    position: relative;
    border: 3px solid #ff6b6b;
    border-radius: 10px;
    color: #5c5858;
}
.item{
    width: 25%;
    height: var(--height);
    line-height:var(--height);
    text-align: center;
    cursor: pointer;
}


.slide{
    width: 25%;
    height: 100%;
    background-color: #ff6b6b;
    left: 0;
    position: absolute;
    z-index: -1;
    transition: all 0.5s ease-out;
    border-radius: 5px;
    display: inline-flex;
}